1. Field of the Invention
This invention relates to the field of structures to absorb solar radiation in liquid flowing in passageways in a panel, the structures being provided with interlocking glazing panels which, together with panels carrying the liquid, may be slidably assembled with rails attached to a supporting structure.
2. The Prior Art
Typical solar panels consist of an assembly of a shallow pan, or collector plate, with water passages attached to the plate or formed with it as part of an extruded structure. A sheet of transparent glazing material covers the collector plate and is sealed to the edges of it so that the water passages are insulated from the atmosphere but can receive the solar radiation through the glazing without being cooled by the air. Some panels have two such transparent sheets and are commonly referred to as double-glazed panels. The solar panels are typically placed on a completed roof and rest on the roofing material that furnishes the required weatherproofing.
Such panels are made up of separate components of different materials that must be hand assembled to form a finished panel. Furthermore, they are not intended to take the place of the customary roofing material and so they constitute an extra expense over the cost of the structure with which they are to be used. If one panel must be serviced, for example to seal a leak or replace the glazing, it is difficult to separate it from the other panels and to replace it after service has been performed on it.
I have previously proposed extruded panels formed of a suitable plastic material, such as Plexiglas, or a polycarbonate material, such as Lexan. It is possible to extrude such material to form panels several feet wide and as long as may be desired. Such panels included several passages for liquid to be heated by solar radiation. These passages were formed side by side and joined one to the other in the extrusion process, thereby forming a passageway plate.
In my previously proposed structure, the cover was also formed in the same extrusion process and spaced fron the passages and attached to them by ribs extending from the passageway plate. The passages carried the liquid to be heated by solar radiation and the cover enclosed a dead-air insulating space over the passages. The opposite edges of the structure included flanges that either interlocked directly with flanges of the next adjacent panels in an overlapping manner to form a waterproof structure or interlocked with a flanged member previously nailed to the roof on which the panels are placed. At least one supporting rib extended downwardly from the liquid passages to the roof to support the panel from the roof with an additional dead-air space between the lower surface of the passageway plate and the roof. This additional dead-air space provided further insulation of the roof and minimized the direct loss of heat from the passages to the roof.
One of the advantages of my prior structure: simplification by extrusion of the passageway plate, ribs, interlocking edge, and cover as a unit, was also sometimes a disadvantage in requiring rather complex extrusion molds. Damage to part of each complex panel could also result in having to replace that entire panel.
Another disadvantage is that during the hot weather in summer, the space enclosed by the structure could get excessively hot. This would occur just at the time that it was unnecessary to run liquid through the passageways to be heated by radiation from the sun, and such excess heat could be detrimental to the plastic or could require that a more expensive extrudable material capable of withstanding such heat be used.